Donald Rumsfeld, the US Defence Secretary, will arrive in Moscow today to focus the coalition's diplomatic campaign on Russia.

Mr Rumsfeld's visit to Russia – following on the heels of a similar visit by Jack Straw, the Foreign Secretary – comes amid rumours of an expected reshuffle of the Russian government, which could reinforce plans by the President, Vladimir Putin, to exploit a policy rethink in Washington since 11 September and make a fresh start in Russian relations with the US.

Mr Straw was in Moscow on Wednesday for talks with his counterpart, Igor Ivanov, and with Sergei Ivanov, the Russian Defence Minister. The Foreign Secretary was the fourth British cabinet minister to visit Moscow since 11 September, a series of visits intended to convince Russia that neither the US nor Britain have any designs on what remains of Russia's regional influence.

Scarcely had the Russian Foreign Minister concluded his joint press conference with Mr Straw in Moscow, than he was on a plane for Washington to discuss arrangements for the summit between presidents Bush and Putin, to be held in America in two weeks' time. Travelling in the opposite direction was Richard Armitage, the US Assistant Secretary of State, for one of a regular round of meetings with Russian officials.

Igor Ivanov's absence from Moscow for the Afghanistan talks was further evidence that the Bush-Putin summit could be his swansong. Moscow is rife with reports of an imminent ministerial reshuffle, in which the chief victim is expected to be the Foreign Minister. He is an accomplished diplomat with a smooth manner but his influence on policy is described by insiders as minimal. He apparently hopes to return to Spain (his former posting as ambassador), where his wife and daughter still spend their time.

The eclipse of Igor Ivanov may enable a shift in Russian policy on George Bush's missile defence project. Having insisted the events of 11 September made missile defence more urgent, Mr Bush had postponed missile tests because Russia believed they would breach its 1972 anti-ballistic missile (ABM) treaty. A report in yesterday's Washington Post set out a detailed scheme of compromises which, it said, the two sides were preparing to agree at the coming summit.

The agenda could include a US undertaking not to revoke the ABM treaty but it would be coupled with Russian agreement for a US missile defence test and development programme: in other words, Russia will turn a blind eye to technical breaches of the treaty for the time being, so long as the US remains committed to the spirit of the treaty.

At the summit, the two sides may agree to reduce the number of strategic warheads each side holds by two-thirds (from 6,000 to fewer than 2,000). The Washington Post's article clearly seems to be an authorised "leak", designed to sound out Russia's response in advance of Mr Rumsfeld's arrival in the capital.

After his Moscow stop-off, Mr Rumsfeld will travel from Moscow to the central Asian states that are providing assistance to the US-led campaign against the Taliban. From there, he will go to India, which was reported to have agreed yesterday to let its navy refuel US ships.